In order to facilitate wireless communication at increasing data rates, various new standards and systems for mobile communication are emerging. An example of an emerging cellular system is 3G Long Term Evolution (3G LTE). 3G LTE systems may operate on radio-frequency (RF) channel bandwidths ranging from 1.25 MHz to 20 MHz. Moreover, data rates up to 100 Mb/s may be supported for the largest bandwidth.
In a mobile radio terminal, such as a mobile telephone, it is desirable to have relatively low power consumption, since the energy resources are normally limited by the capacity of a battery. However, normally a relatively high power consumption is needed in a radio-receiver circuit of the mobile radio terminal in order to support reception of data at relatively high data rates, such as the highest data rates in LTE. In order to e.g. avoid excessively rapid draining of batteries in mobile radio terminals, there is a need for reducing the power dissipation in radio-receiver circuits.
One way of reducing power dissipation is given in U.S. Pat. No. 7,295,645, which discloses a transceiver with scalable analog-to-digital conversion resolution and dynamic range that may be used in a wireless local-area network (WLAN). In a reception mode, i.e. when the transceiver is receiving data, the ADC can be operated in a high-precision mode. In a search mode, i.e. when the transceiver is searching for a scanning for a signal of interest, an analog-to-digital converter (ADC) can be operated in a low-power mode, whereby power can be saved. There is, however, a need to even further decrease power dissipation in radio-receiver circuits.